The United Kingdom would lose more than it would gain if it left the European Union, a Stanford scholar said.

So would other European nations, and the real winners would be countries that seek to divide European unity, said Christophe Crombez, a consulting professor in Stanford’s Europe Center in the Freeman Spogli Institute for International Studies.

Britain is holding a referendum on June 23 to decide whether the country should leave or remain in the European Union.

“It would bring but an illusion of sovereignty,” said Crombez, who studies European Union politics, parliamentary systems, political economy and economic analysis of political institutions. He is an economist from Belgium.

The Stanford News Service recently interviewed Crombez on the upcoming vote, known as “Brexit.”

What is Brexit?

The term Brexit refers to the United Kingdom’s withdrawal from the European Union. Article 50 of the Treaty on European Union allows member states to withdraw.

What are the arguments for and against Brexit?

The campaign for the UK to leave the EU uses the following main arguments: leaving would save UK taxpayers money, since the UK is a net contributor to the EU budget; the UK would no longer have to comply with EU laws it does not want, whereas currently it can be outvoted in EU institutions and forced to adopt laws it opposes; and it would allow the UK to better control migration, whereas EU citizens are currently free to move and work throughout the EU.

These three arguments can easily be refuted, however. The UK does indeed contribute to the EU budget, but the benefits it derives from being part of the EU market far outweigh the budgetary contributions. Moreover, (if Britain were to withdraw) the EU would require the UK to pay into its budget, if it wants to remain part of the EU’s internal market, as it has done with Switzerland and Norway.

Also, about half of UK exports are destined for the EU. If the UK were to leave, it would no doubt want to continue to trade with the EU. UK products would have to conform to EU rules for them to be sold in the EU. UK companies that want to export to the EU would thus continue to comply with EU rules. The difference would be that the UK would no longer be involved in setting those EU rules. Post-Brexit, the rules would thus be less to the UK’s liking than prior to it, and UK companies would comply to these less advantageous rules.

Finally, the EU would impose requirements on immigration and free movement of people on the UK in exchange for free trade with the EU, as it has with other countries in similar situations, such as Norway and Switzerland. Moreover, member states may no longer feel inclined to stop refugees from moving on to the UK if the UK were to leave, which may lead to higher rather than lower immigration.

In addition to these arguments, the Britain Stronger in Europe campaign (which supports the UK remaining in the EU) argues that Britain carries more weight in world politics as part of the EU than on its own, in trade negotiations as well as on security issues, and that a united Europe is better at dealing with (Russian President Vladimir) Putin and other authoritarian rulers, terrorist threats and international crime.

What do you think is the best decision for the United Kingdom to make on this vote?

I see no advantages to leaving the EU. It would bring but an illusion of sovereignty – consider the points above. The vote would have a negative impact on growth in the UK and the rest of the EU and, in fact, the world, and it would weaken the UK, the EU and the West in world politics.

What happens economically to Britain if the country leaves the European Union?

Trade and hence gross domestic product would be negatively affected, especially in the short term. Uncertainty would reduce investment and trade. The UK and the EU would be consumed with the negotiations on the break-up for years. This would prevent both the UK and EU from tackling more important economic and security issues. In the long term, the economy would readjust, but the result would be suboptimal.

What happens to the EU if Britain leaves?

The EU is less dependent on trade with the UK than vice versa. There would be an economic impact, but it would be less substantial. The effect would be more significant for a few countries that trade more with the UK, such as Ireland, Belgium and the Netherlands.

Brexit would, however, deliver a major blow to the idea of European unification. It would weaken the EU impact in world politics and strengthen such rulers as Putin and (Turkish President Recep Tayyip) Erdogan in their dealings with the EU.

Could a British exit open up a Pandora’s Box of other EU countries exiting or spark other regional independence movements, like  Catalonia?

That is quite possible. A number of other countries may want to hold referendums on the EU. Moreover, Brexit is likely to lead to a break-up of the UK. Scotland would likely hold another referendum and decide to leave the UK in order to stay in the EU. The same may be true for Northern Ireland in the long run. Scottish secession may then give other EU regions, such as Catalonia, further incentives to secede.